Advance mechanism for collated screwdriver

ABSTRACT

A driver attachment for driving screws in a collated screwstrip. The attachment having a housing and a slide body slidable axially relative to the housing with the slide body carrying a shuttle slidable transversely relative the slide body. A lever is coupled at one end to the housing and at another end to the shuttle such that reciprocal movement of the housing and slide body axially reciprocally cycles the shuttle transversely. The slide body preferably carries a bearing member which when the slide body approaches a fully extended postion, engages the lever to assist the lever in drawing the shuttle inwardly to advance the screwstrip.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/673,398, filed Jun. 28, 1996, now U.S. Pat. No. 5,775,185,and a continuation-in-part of U.S. patent application Ser. No.08/511,945, filed Aug. 7, 1995 and issued as U.S. Pat. No. 5,568,753.

SCOPE OF THE INVENTION

This invention relates generally to a screwdriver for driving collatedscrews which are joined together in a strip and, more particularly, toan advance mechanism to advance the screwstrip in the screwdriver.

BACKGROUND OF THE INVENTION

Collated screwstrips are known in which the screws are connected to eachother by a retaining strip of plastic material. Such strips are taught,for example, by U.S. Pat. No. 4,167,229, issued Sep. 11, 1979 and itsrelated Canadian Patents 1,040,600 and 1,054,982, as well as U.S. Pat.No. 4,930,630, the disclosures of which are incorporated herein byreference. Screws carried in such screwstrips are adapted to besuccessively incrementally advanced to a position in alignment with andto be engaged by a bit of a reciprocating, rotating power screwdriverand screwed into a workpiece. In the course of the bit engaging thescrews and driving it into a workpiece, the screw becomes detached fromthe plastic strip leaving the strip as a continuous length.

In the use of such collated screwstrips in screwdrivers, the stripserves a function of assisting in guiding the screw into a workpieceand, to accomplish this, the strip is retained against movement towardsthe workpiece. In the screwstrip, each screw to be driven has itsthreaded shaft threadably engaged in a threaded sleeve of the strip suchthat on the screwdriver engaging and rotating each successive screw, thescrew turns within the sleeve which acts to guide the screw as it movesforwardly into threaded engagement into the workpiece. Preferably, onlyafter the tip of the screw becomes engaged in the workpiece does thehead of the screw come into contact with the sleeves. Further, forwardmovement of the screw into the workpiece then draws the head downwardlyto engage the sleeve and to rupture the sleeve by reason of the forwardmovement of the head with the strip retained against movement towardsthe workpiece. The sleeve preferably is configured to have fragilestrips which break on the head passing through the sleeve such that thestrip remains intact as a continuous length. Since the strip is acontinuous length, on advancing the screwstrip with each successivescrew to be driven, it necessarily results that portion of the stripfrom which each screw has been driven are also advanced to exit from thepower screwdriver.

Known power screwdrivers for driving such collated screwstrips includeU.S. Pat. No. 4,146,071 to Mueller et al, issued Mar. 27, 1976, and U.S.Pat. No. 5,186,085 to Monacelli, issued Feb. 16, 1993. Such known powerscrewdrivers include a rotatable and reciprocally moving screwdrivershaft which is turned in rotation by an electric motor. A screwdrivingbit forms a forwardmost portion of the shaft for engaging the head ofeach successive screw as each screw is moved into a driving position,axially aligned under the screwdriver shaft.

An important aspect of such a power screwdriver is the manner andaccuracy with which the screws are advanced and positioned so as to beproperly aligned axially under the screwdriver shaft for successfulinitial and continued engagement between the bit and the screwdriverhead in driving a screw fully down into a workpiece. In the device ofMueller et al, a guide channel is provided through which the screwstripis advanced. The guide channel is sized to receive screws of specifichead size and minimum length. The guide channel is formed as an integralpart of a sliding body which also carries other components of a screwadvance mechanism to engage the screwstrip and advance the screwstrip inthe guide channel. The screws are successively advanced into position inalignment with the screwdriver shaft with the heads of the screws beingurged into abutment with a stop which is to locate the screw head. Thestop typically defines a radial extent of a boreway through which theshaft and screw head axially move as the screw is driven. The shaft isaxially movable in the boreway in a reciprocal manner to engage thescrew and drive it into a workpiece. After each screw is driven theshaft retracts and a subsequent screw carried on the screwstrip isadvanced sideways into the boreway, engaging the stop so as to bealigned under the shaft.

Known power drivers for collated screws have a slide body which isreciprocally slidable relative a housing in a normal cycle of operation.Known screw advance mechanisms are coupled between the slide body andhousing to translate relative movement of the slide body and housinginto a cyclical cycle of advance of the screwstrips.

Known screw advance mechanisms suffer the disadvantage that they arecomplex and typically involve a number of components which need to beshrouded and protected. For example, in the device of Mueller et al,U.S. Pat. No. 4,146,871, the advance mechanism comprises threeinterrelated lever members together with a camming roller which cams ona camming surface. A primary spring biases the slide body to an extendedposition relative the housing. A secondary spring biases the levermembers to urge the roller into the screwstrip towards the fullyadvanced position. The secondary spring has the disadvantage ofrequiring additional forces for operation so as to telescope the slidebody into the housing and to overcome friction in telescoping or inextension. Known screwstrip advance mechanisms are unduly complex,expensive to manufacture, cumbersome, bulky and inconsistent in theirfeatures with providing a lightweight tool of minimum size.

SUMMARY OF THE INVENTION

To at least partially overcome these disadvantages of the prior art, thepresent invention provides, in one aspect, in a screwdriver for drivingscrews having a housing and a slide body slidable axially relative tothe housing with the slide body carrying a shuttle slidable relative theslide body transversely, a lever is coupled at one end to the housingand at another end to the shuttle such that reciprocal movement of thehousing and slide body axially reciprocally cycles the shuttletransversely. The slide body preferably carries a bearing member which,when the slide body approaches a fully extended position, engages thelever to assist the lever in drawing the shuttle inwardly to fullyadvance the screwstrip.

An object of the present invention is to provide an improved screwstripadvance mechanism for power screwdrivers for driving collated screws.

Another object is to provide a simple screwstrip advance mechanism whichhas a minimum of parts yet ensures proper advance of a screwstrip.

Accordingly, in one aspect, the present invention provides an apparatusfor driving with a power driver a screwstrip comprising threadedfasteners, such as screws or the like, which are joined together in astrip comprising:

a housing;

an elongate drive shaft for operative connection to a power driver forrotation thereby and defining a longitudinal axis;

a slide body coupled to the housing for displacement parallel to theaxis of the drive shaft between an extended position and a retractedposition;

the slide body having a guide channel for said screwstrip transverse tothe axis,

a shuttle carried on the slide body movable relative the slide bodytransverse to the axis towards and away from the axis,

the shuttle carrying pawl means for engagement with the screwstrip toadvance the screwstrip with movement of the shuttle towards the axis toplace successive of the fasteners into axial alignment with the driveshaft for driving by the drive shaft, and

a lever having a first end coupled to the shuttle and a second endcoupled to the housing whereby movement of the slide body axiallyrelative the housing (a) towards the extended position moves the shuttletowards the axis and (b) away from the extended position moves theshuttle away from the axis and, preferably, with a bearing member on theslide body which engages the lever intermediate the first end and thesecond end of the lever when the slide body is proximate the extendedpostion such that when the slide body moves axially towards the extendedposition, the bearing member urges the lever to assist moving theshuttle towards the axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects and advantages of the present invention will appear fromthe following description taken together with the accompanying drawings,in which:

FIG. 1 is a pictorial view of a power screwdriver in accordance with afirst preferred embodiment of the present invention;

FIG. 2 is an exploded pictorial view of the elements of the driverattachment shown in FIG. 1;

FIG. 3 is a partially exploded pictorial view of the opposite side ofthe driver attachment to that shown in FIG. 2 and with a screwstrippositioned therein;

FIG. 4 is a schematic partially cross-sectional view of the driverattachment of FIG. 1 in a fully extended position as seen in FIG. 1through a plane passing through the longitudinal axis of the drive shaftand centrally of the screws in the screwstrip;

FIG. 5 is a view identical to FIG. 4 but with the driver attachment in apartially retracted position in driving a screw into a workpiece;

FIG. 6 is an end view of the nose portion of FIG. 2;

FIGS. 7 to 15 are side views of the driver attachment of FIGS. 1 to 6showing the attachment in successive positions in a cycle of operation,with FIGS. 7 and 15 showing the attachment in the same fully extendedposition and FIG. 10 showing the attachment in the fully retractedposition.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is made to FIG. 1 which shows a complete power screwdriverassembly 10 in accordance with the present invention. The assembly 10comprises a power driver 11 to which a driver attachment 12 is secured.The driver attachment 12 is adapted to receive a collated screwstrip 14carrying spaced screws 16 to be successively driven.

Reference is made to FIG. 2 showing an exploded view of major componentsof the driver attachment 12 as housing 18 and a slide body comprising arear portion 22 and a removable nose portion 24. FIGS. 4 and 5 show incross-section the interaction of these components.

The rearmost end 26 of the housing 18 has a rearwardly directed socket27 with a longitudinal slot 28 in its sidewall to receive and securelyclamp the housing 18 onto the housing 30 of the power driver 11 so as tosecure the housing 18 of the driver attachment to the housing 30 of thepower driver against relative movement. The power driver 11 has a chuck32 rotatable in the driver housing 30 by an electric motor (not shown).The chuck 32 releasably engages the driver shaft 34 in known manner.

As seen in FIG. 4, the slide body 20 is slidably received in the housing18 with the driver shaft 34 received in a bore passing through the rearportion 22 and nose portion 24 of the slide body 20. A compressionspring 38 disposed between the housing 18 and the rear portion 22coaxially about the driver shaft 34 biases the slide body away from thehousing 18 from a retracted position towards an extended position. Asshown, the spring 38 is disposed between the housing 18 and the rearportion 22. Key members or slide stops 25, best shown in FIG. 2, aresecured to the rear portion 22 of the slide body. The two slide stops 25slide in two longitudinal keyway slots 40 on each side of the partcylindrical sidewall 42 of the housing 18 to key the rear portion 22 ofthe slide body to the housing 18 against relative rotation and toprevent the slide body being moved out of the housing 18 past a fullyextended position.

The rear portion 22 comprises a generally cylindrical element 44 securedto the nose portion 24.

The nose portion 24 includes a guide tube 75 and a feed channel element76 extending radially from the guide tube 75. The feed channel element76 has a channelway 88 to receive a screwstrip and via which screws ofthe screwstrip are advanced into the guide tube 75 for drivingsuccessively by the driver shaft 34.

A shuttle 96 is slidably mounted on the feed channel element 76 forsliding in a raceway 94 transverse to the axis of the drive shaft 34towards and away from the guide tube 75. The shuttle 96 carries a pawl99, best seen in FIG. 6, to engage the screwstrip and to advance thescrewstrip when the shuttle 96 moves towards the guide tube 75.

A lever 48 has a first end 49 coupled to the shuttle 96 and a second end50 coupled to the housing 18. In this regard, shuttle 96 carries ashuttle mount post 51 having a reduced diameter pivot pin 52 at its endand presenting shuttle shoulder surface 53.

Lever 48 has a circular opening 54 at its first end sized to journal onpin 52. A screw 55 carrying a washer 56 secures the first end of thelever 48 to the post 51 for pivoting on pin 52 with a rear surface 57 ofthe lever 48 supported on shoulder surface 53.

Housing 18 carries a housing mount post 58 having a reduced diameterpivot pin 59 at its end and presenting housing shoulder surface 60.

Lever 48 has, at its second end, a lost motion slot 61 with semicircularends. Slot 61 is sized to receive pin 59 therein, permitting relativesliding along the length of the slot and relative pivoting about theaxis of the pin 59 when the pin is in any location in the slot. A screw62 carrying a washer 63 secures the second end of the lever 48 to thepost 58 for sliding and pivoting of slot 61 on pin 59 with the rearsurface 57 of the lever 48 supported on the shoulder surface 60.

Due to the lever 48 being coupled between the housing 18 and shuttle 96,relative sliding of the slide body 20 and housing 18 results in slidingof the shuttle relative the slide body 20.

The slide stop 25 secured to the slide body 20 on the same side of theattachment as the lever 48 includes a key portion 64 and a bearing plate65. The key portion 64 extends through the keyway slot 40 so as tolocate the bearing plate 65 radially outward of the side wall 42 of thehousing 18. The slide stop 25 carrying the bearing plate 65 is securedto the body portion by a bolt 70 extending through opening 67. Thebearing plate 65 has a forwardly directed bearing surface 68 adapted toengage with a camming surface 69 on lever 48. In an assembled assembly,the bearing plate 65 is axially inline with the lever 48 axiallyrearward of the lever 48 such that when the slide body 20 is proximatethe extended position, the bearing surface 68 of the bearing plate 65engages the camming surface 69. The support shoulders 53 and 60 supportthe lever 48 axially inline with the bearing plate 65 and with both thebearing plate 65 and lever 48 disposed in a plane which is parallel aplane in which the shuttle 96 slides relative the slide body 20. Eachpivot pin 52 and 59 is disposed about an axis normal such plane.

Operation of the attachment is now described with reference to FIGS. 7to 15, each of which show a side view of the assembled attachment ofFIGS. 1 to 6 in successive steps in a cycle of operation. FIG. 7 showsthe attachment in a fully extended position which position is also shownin cross-section in FIG. 4. As seen in FIG. 4, the shuttle 96 is fullyadvanced such that its pawl 99 is positioned to locate the screw to bedriven axially in the guide tube 75. Also as seen in FIG. 4, the bit 122on the driver shaft 34 is spaced rearwardly from the screw to be driven.FIG. 7 shows the pin 59 as received in the rearward end of the lossmotion slot 61. The bearing plate 65 is fully seated on the cammingsurface 69 of lever 48.

In retraction of the attachment from the position of FIG. 7 to theposition of FIG. 8, the pin 59 slides forwardly in the loss motion slot61. The bearing plate 65 remains fully seated on lever 48. The lever 48does not pivot on either pin 52 or pin 59 but moves directly forwardlyparallel the axis so that the shuttle 96 does not slide in its racewaybut rather maintains a constant, stationary advanced position relativethe raceway such that the screw to be driven is maintained in the sameposition axially aligned with the driver shaft 34. The retraction of theslide body 20 relative the housing 18 with the shuttle 96 in theadvanced position is sufficient that with the shuttle 95 in the advancedposition, the bit 122 on the driver shaft 34 engages the screw to bedriven, seating the bit in the recess 213 of the screw head andcommencing to drive the screw towards a workpiece. With the bit seatedand engaged in the recess of the screw head, the bit holds the screw andthereby the screwstrip against movement.

In retraction of the attachment from the position of FIG. 8 to theposition of FIG. 9, the lever 48 pivots about pin 59 in the forward endof slot 61 and about pin 52. The lever assumes an angulation in which itextends more transversely to the axis and the lever slides shuttle 96transversely away from the driver shaft to a fully withdrawn position.Preferably, the shuttle 96 does not move from the fully advancedposition until the bit is ensured to be engaged in the screw with theshuttle 96 moving towards the withdrawn position merely in time to clearthe head of the screw as it is driven forwardly. In FIG. 8, a line drawnbetween pin 52 and pin 59 is normal the axis of the driver shaft 34. Thebearing plate 65 is carried rearwardly with the slide body out ofengagement with the lever 48.

In retraction of the attachment from the position of FIG. 9 to the fullyretracted position of FIG. 10, the pin 52 slides from the front to therear end of the loss motion slot 61 such that the shuttle 96 remains insubstantially the same fully withdrawn position as in FIG. 9.

From the fully retracted position of FIG. 10, the attachment now extendssuccessively through the positions shown in FIGS. 11, 12, 13 and 14 andthen to the fully extended position shown in FIG. 15 which is the sameas that shown in FIG. 7.

In initial extension from FIG. 11 to FIG. 12, the pin 52 slides from therear end of the loss motion slot 61 whereby the shuttle 96 remains insubstantially the same fully advanced position as in FIG. 11. FIG. 12corresponds in relative positioning of the lever to FIG. 9.

In extension, the attachment assumes in succession the position shownfrom FIG. 12 through FIGS. 13 and 14 to FIG. 15 with lever 48 pivotingabout pin 59 with the pin received in the rear end of the slot 61 andthe movement of the lever 48 drawing the shuttle 96 towards the axisfrom the fully withdrawn position of FIG. 11 to the fully advancedposition of FIG. 15. In shuttle 96 moving towards the axis, the pawl 99engages the screwstrip and advances the screwstrip towards the axis tolocate the next screw to be driven axially in line with the driver shaft34. When FIGS. 11 to 15 are viewed in progression, the bearing plate 65is shown to slide forwardly with the slide body 20 relative the housingfrom positions rearward of the lever 48 into positions in engagementwith the lever 48 as the slide body 20 approaches and becomes proximatethe fully extended position. FIG. 13 shows the position in which thebearing plate 65 first engages the lever 48. The bearing plate 65 andlever 48 remain in continued engagement in extension from FIG. 13 toFIG. 15 in which the bearing surface 68 of bearing plate 65 is fullyseated in the complementary shaped camming surface 69 of lever 48.

The engagement of lever 48 by the bearing plate 65 assists in supplyingincreased forces to the lever to draw the shuttle inwardly towards theaxis and overcome any resistance offered by the screwstrip to advancing.By the bearing plate 65 engaging the lever 48 between the first andsecond ends of the lever and thereby closer to the first end than thepin 59, the bearing plate 65 acts as a fulcrum closer to the loadapplication site at pin 52 to increase the mechanical advantage. Thecontact point or fulcrum between the bearing plate 65 and the lever 48shifts forwardly down the lever 48 as the slide body and housingrelatively retract and thus provide increased mechanical advantage.

The bearing surface 68 and camming surface 69 are complementarilyconfigured such that they impart to the lever 48 forces to cause thelever 48 to follow the same relative motion as that dictated by theguiding of the lever 48 on the two pins 52 and 59. The riding of thebearing surface 68 on the camming surface 69 assists in urging theshuttle 96 towards the driver shaft and in overcoming resistance toadvance of the screwstrip.

The fully extended position of FIG. 15 is identical to that of FIG. 7and from which a further cycle of operation may commence.

In the retraction and extension of the attachment from the position ofFIG. 7 through FIGS. 8 to 15, the lever does not, as seen in side viewin these figures, substantially extend beyond the edges of the shuttlebody and housing. This is advantageous to keep the relative profile andbulk of the attachment at a minimum.

A loss motion mechanism comprising the slot 61 and pin 59 is provided atthe second end of the lever 48 to permit the attachment to initially beretracted from the position of FIG. 7 to the position of FIG. 8 with theshuttle 96 and its pawl 99 not moving so as to retain the screw to bedriven axially inline with the driver shaft. In an alternate version, aloss motion slot could be provided at the first end of the leverextended rearwardly when in the position of FIG. 7 and with a circularbore at the second end. With the bearing plate modified to be spacedrearwardly on the slide body from its location shown in FIG. 7 adistance equal to the length of the slot, a similar operation could beachieved to that with the illustrated attachment.

It is, however, not necessary that a loss motion mechanism be provided.For example, if a mechanism is provided to prevent movement of anadvanced screwstrip away from the driver shaft which mechanism isindependent of the shuttle 96, then there is no need for the loss motionmechanism when the attachment retracts from the position of FIG. 7 tothe position of FIG. 8. A mechanism to prevent movement of the advancedscrewstrip towards the withdrawn position could comprise a pawl similarto pawl 99 which would extend into the channelway 88 but be fixedlymounted to the channelway 88 and would permit advance of the screwstripbut prevent withdrawal of the screwstrip.

To the extent the retraction stroke does not retract the slide bodysubstantially beyond the position shown in FIG. 9, then a loss motionmechanism is not necessary. However, even if a cycle of operation of theattachment includes moving past the position in FIG. 9, then theattachment may be adapted to interact with a screwstrip such that themovement of the shuttle 96 inward between FIG. 9 and FIG. 10 and outwardbetween FIG. 10 and FIG. 11 does not affect proper advance of the nextscrew.

In the preferred embodiment in movement from FIG. 11 to FIG. 12, the pin59 slides to the rear end of slot 61 and the shuttle 96 is stationary inits raceway. This is not necessary, however, is preferred to assist inpreventing the shuttle 96 from advancing the screwstrip until the drivershaft is withdrawn as to prevent the advancing screw from engaging thewithdrawing driver shaft. Such operation may, in part, be assured byhaving the initial resistance to the shuttle 96 sliding towards thedriver shaft greater than the resistance to sliding of the pin 59 inslot 61. The relative resistance of the shuttle 96 to movement could beadjusted by modification of the raceway and/or providing a spring tobias the shuttle 96 towards or away from the advanced position, forexample, about guide pin 72. FIG. 6 shows a preferred helical coilspring 25 in a compressed condition disposed about guide pin 72 andextending between the shuttle 96 and one end wall of the raceway 94 tobias the shuttle 96 away from the end wall and towards the guide tube75. This coil spring 25 is not shown in FIG. 3 to assist in clearlyshowing the guide pin 72.

The bearing plate 65 is advantageous to provide smooth operation byassisting in moving the shuttle 96 towards the axis when the slide body20 is proximate the fully extended position. The provision of a bearingplate 65 is not necessary but is preferred.

The nose portion 24 has a generally cylindrical screw guide element orguide tube 75 arranged generally coaxially about longitudinal axis 52and a flange-like screw feed channel element 76 extending radially fromthe guide tube 75.

The guide tube 75 has a cylindrical portion 77 at its rear end with acylindrical exterior surface sized to be closely received, preferably ina friction fit, within a forwardly opening cylindrical bore 78 in theforward end of the rear portion 22. A radially extending key 80 isprovided to extend from the cylindrical portion 77 of the nose portion24 to be received in a correspondingly sized keyway slot 82 in the rearportion 22 as best seen in FIG. 4 and 7 to secure the nose portion 24 tothe rear portion 22 against relative pivoting about the longitudinalaxis 52.

The guide tube 75 has a cylindrical bore or guideway 82 extendingaxially through the guide tube with the guideway 82 delineated andbordered by a radially extending cylindrical sidewall 83 and open at itsforward axial end 84 and at its rearward axial end 85.

The guide tube 75 has a rearward section adjacent its rear end 85 inwhich the sidewall 83 extends 360° about the guideway 82. Forward of therearward section, the guide tube has a forward section best seen in FIG.4 and which has an access opening 86, shown in the drawings as being onthe right hand side of the guide tube 75. Screw access opening 86 isprovided to permit the screwstrip 14 including retaining strip 13 andscrews 16 to move radially inwardly into the guideway 82 from the rightas seen in FIG. 4 and 5. Each screw preferably has a head 17 with adiameter marginally smaller than the diameter of the sidewall 83. Itfollows that where the head of the screw is to enter the guideway 82,the screw access opening must have circumferential extent of at least180°. Where the shank 208 of the screw is to enter the guideway, thescrew access opening may have a lesser circumferential extent.

In the forward section, the sidewall 83 of the guide tube 75 engages theradially outermost periphery of the head 17 of the screw 16, to axiallylocate the screw head 17 coaxially within the guideway 82 in axialalignment with the drive shaft 34. In this regard, the sidewall 83preferably extends about the screw sufficiently to coaxially locate thescrew head and thus preferably extend about the screw head at least120°, more preferably, at least 150° and most preferably about 180°.

An exit opening 87, shown towards the left hand side of the guide tube75 in FIGS. 4 and 5, is provided of a size to permit the spent plasticstrip 13 from which the screws 16 have been driven to exit from theguideway 82. The exit opening 87 is shown as an opening bordered on itsfront, rear and two sides to assist in retaining the spent strip in theexit opening. Forwardly of the exit opening 87, the sidewall 83 of theguide tube 75 is shown as extending greater than about 180° about thelongitudinal axis 52 so as to continue to provide a sidewall 83 whichcan assist and positively coaxially guiding the head 17 of a screw 16being driven.

The screw feed channel element 76 is best seen in FIGS. 3 and 4 asproviding a channelway 88 which extends radially relative thelongitudinal axis 52 to intersect with the guideway 82 in the guide tube75. In this regard, the channelway 88 opens to the guideway 82 as thescrew access opening 86. The channelway 88 provides a channel of across-section similar to that of the screw access opening 86 from thescrew access opening 86 to a remote entranceway opening 90. Thechannelway 88 is defined between two sidewalls 91 and 92 joined by a topwall 93. The major sidewall 91 is shown as extending from the heads 17of the screws 16 forwardly to at least partially behind the plasticretaining strip 13. The lesser sidewall 92 is shown as extending fromthe heads 17 of the screws 16 forwardly to above the plastic strip 13.Stopping the lesser sidewall from extending down over the strip 13assists in reducing friction between the strip 13 and the lessersidewall. The sidewalls 91 and 92 define the channelway 88 with across-section conforming closely to that of the screwstrip 14 and itsstrip 13 and screws 16 with an enlarged width where the heads of thescrews are located and an enlarged width where the retaining strip 13 isprovided about the screws. The sidewalls 91 and 92 also have an enlargedfunnelling section at the entranceway opening 90 which tapers inwardlyto assist in guiding the screwstrip to enter the channelway.

As best seen in FIG. 3, the major sidewall 91 is provided on itsexterior back surface with a raceway 94 extending parallel thechannelway 88 and in which the shuttle 96 is captured to be slidabletowards and away from the guide tube 75 between an advanced positionnear the guide tube and a withdrawn position remote from the guide tube.

The shuttle 96 has a guide bore 71 therethrough to be received about aguide pin 72 which has each of its ends secured in portions forming endwalls of the raceway 94 such that the guide pin 72 positively retainsand guides the shuttle 96 in the raceway 94.

Shuttle 96 carries the pawl 99 to engage the screwstrip 14 and withmovement of the shuttle 96 to successively advance the strip one screwat a time. As seen in FIG. 6, the shuttle 96 has a fixed post 100 onwhich the pawl 99 is journalled about an axis parallel the longitudinalaxis 52 about which the driver shaft 34 rotates. The pawl 99 has a strippusher arm 101 which extends through a slot 103 in the major sidewall 91to engage and advance the screwstrip. The pawl 99 has a manual releasearm 102 away from pusher arm 101 and which extends out through a slot104 in the shuttle 99. A torsional spring is disposed about post 100between pawl 99 and shuttle 96 and urges the pusher arm 101 clockwise asseen in FIG. 6. The spring biases the pusher arm 101 into the screwstrip14. The engagement of release arm 102 on the right hand end of slot 104limits the pivoting of the pawl 99 clockwise to the position shown inFIG. 6.

The pusher arm 101 of the pawl 99 has a cam face 107. On the shuttlemoving away from the guide tube 75 towards the withdrawn position, i.e.,to the left in FIG. 6, the cam face 107 will engage the screws 16 and/orthe strip 13 and permit the pusher arm 101 to pivot about post 100against the bias of spring so that the pusher arm 101 may move with theshuttle to the left.

The pusher arm 101 has an engagement face 108 to engage the screws 16and/or strip 13. On the shuttle moving towards the guide tube 75 towardsthe advanced position, i.e., to the right in FIG. 6, the engagement face108 will engage the screws 16 and/or strip 13 and advance the screwstripto the right as seen in FIG. 6 so as to position a screw 16 into theguideway 82 in a position to be driven and to hold the screwstrip 14against movement towards the left. Preferably, as shown in FIG. 4, theengagement face 108 of the pusher arm engages the screw between its head17 and the strip 13 as this has been found advantageous, particularly toavoid misfeeding with a nose portion 24 as shown with engagement of thescrew heads in the channelway 88 and engagement of the spent strip 13'with the support surface 125.

The release arm 102 permits manual withdrawal of the screwstrip 14. Auser may with his finger or thumb manually pivot the release arm 102against the bias of spring so that the pusher arm 101 and its engagementface 108 is moved away from and clear of the screwstrip 14 whereby thescrewstrip may manually be withdrawn as may be useful to clear jams orchange screwstrips. As seen in FIG. 7, when the assembly is in the fullyextended position, the release arm 102 is accessible to one side of thelever 48. In more retracted positions, such as shown in FIGS. 9 to 13,the release arm 102 is still manually accessible under the lever 48,however, with the lever 48 advantageously shielding release arm 102 foraccidental engagement.

Reference is now particularly made to FIGS. 3 and 6 which show apreferred configuration of the screw feed channel element whichfacilitates ready insertion advance and withdrawal of screwstrips. Ascrewstrip may be inserted into the channelway 88 merely by pushing ascrewstrip into the entrance 90. On pushing the screwstrip inwardly, thescrewstrip will engage the cam face 107 of the pusher arm 101 overcomingthe bias of a torsional spring disposed about the post 100 andpermitting the screwstrip to slide towards a fully advanced position. Towithdraw a screwstrip, release arm 102 is manually engaged to withdrawthe pusher arm 101 away from engagement of the screwstrip. Thechannelway 88 is configured to minimize friction between the screwstripand the channelway yet provide for easy guiding and insertion. It is forthis purpose that the major side wall 91 of the channelway preferablyextends from the head 17 of the screws forwardly to behind the plasticretaining strip 13 and not any substantial distance past the plasticretaining strip 13. Similarly, the lesser side wall 92 of the channelwayextends from the head 17 of the screws down forwardly to above theplastic strip 13. It is greatly advantageous that the lesser side wall92 not extend down over the plastic strip 13 to assist in reducingfriction. As well, a bottom edge 74 of the lesser side wall is disposedrearwardly of a rearwardly directed surface 223 of the retaining strip13 and can provide a camming surface to loosely engage the rearwardlydirected rear surface 223 of the screwstrip to further assist andenhance sliding and guiding of the screwstrip.

With the lever 48 coupled to the shuttle 96 and to the housing 18,sliding of the slide body 20 and the housing 18 in a cycle from anextended position to a retracted position and then back to an extendedposition results in reciprocal pivoting of the lever 48 which slides theshuttle 96 between the advanced and withdrawn position in its raceway 94and hence results in the pawl 99 first retracting from engagement with afirst screw to be driven to behind the next screw and then advancingthis next screw into a position to be driven.

The screw feed advance mechanism carried on the nose portion has beenillustrated merely as comprising a reciprocally slidable shuttlecarrying a pawl. Various other shuttle configurations may be adoptedwith the shuttle moving along a pre-set pathway which, preferably, isstraight but may be curved. For example, the shuttle could be supportedas the end of a pivoting arm with the pathway being an arc in a planeparallel to a plane including the lever 48.

The nose portion 24 is removable from the rear portion 22. The noseportion 24 and rear portion 22 may be coupled together by axiallyinserting the cylindrical portion 77 of the guide tube 75 into the bore78 in the rear portion 22 with the key 80 aligned with the keyway slot82 and with the front end 56 of the forward arm 54 of the lever 48aligned with the opening 98 in the shuttle 96. Thus, the removable noseportion 24 may be coupled to the rear portion 22 merely by axiallyaligning the nose portion and the rear portion and moving the twoelements together in a direction parallel the longitudinal axis 52.

With the nose portion 24 held on the rear portion 22 by a friction fit,the nose portion 24 can manually be removed by a user merely by themanual application of force. The nose portion 24 is removable from therear portion 22 merely by disengaging one of the ends of the lever 48from its respective post slot 59, for example, by disengaging the firstend of the lever 48 from post 51 or post 58 as by removing either screw55 or 62 but otherwise without disassembly or uncoupling of any of theremainder of the screwdriver assembly 10. Thus, the nose portion 24 isremovable without otherwise uncoupling of the rear portion 22 relativeany of the housing 18, spring 38, power driver 11 or driver shaft 34.Rather than screws 55 or 62, a quick release mechanism could beprovided.

The nose portion 24 carries the guide tube 75 with its screw locatingguideway 82, the screw feed channel element 76 with its channelway 88,and screw feed advance mechanism with the reciprocating shuttle 96 andpawl 99 to advance the screwstrip 14 via the channelway 88 into theguideway 82. Each of the guideway 82, channelway 88 and shuttle 96 arepreferably customized for screwstrips and screws or other fasteners of acorresponding size. In this context, size includes shape, head diameter,shaft diameter, retaining strip configuration, length, spacing of screwsalong the retaining strip and the presence or absence of washers amongstother things. Different nose portions 24 are to be configured fordifferent screwstrips and screws. The different nose portions 24 areeach compatible with the same rear portion 22 and are readilyexchangeable so as to permit the driver attachment to be readily adaptedto drive different screwstrips and screws.

Many changes can be made to the physical arrangement of the nose portion24 to accommodate different screws and fasteners. For example, thecross-sectional shape of the channelway 88 can be changed as can thediameter of the guideway 82. The length of the sidewalls 91 and 92 aboutthe channelway 88 can be varied to accommodate different size screwswhich may require greater or lesser engagement.

In contrast with the removable nose portion 24 which is intended to beprovided in many different replaceable configurations, the remainder ofthe driver attachment is preferably of a constant unchangedconfiguration. In this regard, the remainder of the driver attachmentmay be characterized by the housing 18, rear portion 22 of the slidebody 20, drive shaft 34 and spring 38 together with a screw feedactivation mechanism comprising the lever 48 and bearing plate 65. Thisscrew feed activation mechanism is activated by relative movement of thehousing 18 and rear portion 22 and serves to engage and move the screwfeed advance mechanism comprising the shuttle 96 and pawl 99 carried onthe nose portion 24.

While the illustrated embodiment shows the slide body 20 as formed witha removable nose portion, this is not necessary and the nose portion 24and rear portion 22 need not be separable.

The construction of the housing 18 and slide body 20 provide for acompact driver attachment. The housing 18 has a part cylindrical portionformed by sidewall 301. The slide body 20 as best seen in FIG. 3comprising the rear portion 22 and nose portion 24, has a partcylindrical portion of a uniform radius sized to be marginally smallerthan the sidewall 301 of the housing 18. The sidewall 301 extendscircumferentially about the part cylindrical portion of the slide body20 to retain the slide body 20 therein.

The housing is open at its front end and one side to permit the screwfeed channel element 76 to slide into and out of the housing 18.Concentrically located about the drive shaft 34 is the spring 38, thepart cylindrical portions of the slide body 20, and the part cylindricalportions of the housing 18. The spring 38 biases the slide body to theextended position relative the housing and, in so doing, provides thefeeding forces to advance the screwstrip as by the lever 48 moving theshuttle 96. In the preferred embodiment, only one spring 38 is shown andthis is preferred. Spring 38 is not necessary and some other mechanismmay be provided to move the slide body relative the housing in a cyclicmanner for operation.

The driver attachment is provided with an adjustable depth stopmechanism which can be used to adjust the fully retracted position, thatis, the extent to which the slide body 20 may slide into the housing 18.The adjustable depth stop mechanism is best seen in FIGS. 2 and 3 ascomprising an elongate rod 110 slidably received in an elongate openended bore 111 provided in the sidewall 42 of the housing 18 andextending parallel to longitudinal axis 52.

A depth setting cam member 114 is secured to the housing 18 for rotationabout a pin 116 parallel the longitudinal axis 52. The cam member 114has a cam surface 115 which varies in depth, parallel the longitudinalaxis 52, circumferentially about the cam member 114. A portion of thecam surface 115 is always axially in line with the rod 110. A spring 113biases the rod 110 rearwardly such that the rear end 117 of the rodengages the cam surface 115. The spring 112 is disposed between thehousing and a pin 113 on the rod. By rotation of the cam member 114, theextent to which the rod 110 may slide rearwardly is adjusted.

The rod 110 has a front end 118 which extends forwardly from bore 111for engagement with rearwardly directed annular stop surface 119provided on the nose portion 24 of the slide body. The slide body 20 isprevented from further sliding into the housing 18 when the front end118 of the rod 110 engages the stop surface 119. The extent the slidebody 20 may slide into the housing 18 is determined by the length of therod 110 and the depth of the cam member 114 axially in line with therod. The cam member 114 is preferably provided with a ratchet-likearrangement to have the cam member 114 remain at any selected positionbiassed against movement from the selected position and with circularindents or depressions in the cam surface 115 to assist in positiveengagement by the rear end 117 of the rod. The cam member 114 isaccessible by a user yet is provided to be out the way and not interferewith use of the driver attachment. The depth stop mechanism controls theextent to which screws are driven into a workpiece and thus controls theextent of countersinking. As the depth stop mechanism controls thedistance from the workpiece the bit 122 must stop, a given countersinksetting will be effective even if strips are switched to use screws of adifferent length. Adjustment is not required merely because differentlength screws are to be used.

The nose portion 24 may be customized for use in respect of differentsize screws by having the location of the stop surface 119 suitablyprovided axially on the nose portion 24 as may be advantageous for useof different size screws.

The driver shaft 34 is shown in FIGS. 4 and 5 as carrying a split washer120 engaged in an annular groove near its rear end 121 to assist inretaining the rear end of the driver shaft in the socket 27 of thehousing 18. The driver shaft 34 is provided with a removable bit 122 atits forward end which bit can readily be removed for replacement byanother bit as for different size screws. Such bits include sockets andthe like in any replacement bits will preferably be of an outsidediameter complementary to the inside diameter of the guideway 82 in acorresponding replacement nose portion adapted for use with acorresponding sized screws. To accommodate bits of increased diameterover the bit shown in FIGS. 4 and 5 the guideway 82 of the guide tube 75may be provided with an increased radius, at least commencing at thelocation where the bit may have an enlarged diameter and extendingforwardly therefrom. The guideway 82 in the guide tubes 75 may thus havea step configuration with the sidewall 83 being of a reduced diameterwhere the driver shaft 34 enters the rear of the guide tube 75 and thesidewall 83 may then increase to an enlarged diameter forwardly toaccommodate an enlarged bit such as a socket.

The rear portion 22 is shown in FIGS. 4 and 5 as having a radiallyinwardly extending annular flange 19 which provides the end of theforwardly opening bore 78 as well as the end of a rearwardly openingbore 79 within which the spring 38 is received. The annular flange 19has an opening therethrough of a diameter slightly larger than thediameter of the driver shaft 34 so as to assist in journalling thedriver shaft therein. The opening through the annular flange 19 mayhowever be increased so as to facilitate the use of driver shafts 34having enlarged diameters as well as a driver shafts 34 having reduceddiameters.

Insofar as the driver shaft 34 has a removable bit 122, it is preferredthat as shown, when the driver attachment 12 is in the fully extendedposition and the nose portion 24 is removed, the bit 122 be readilyaccessible for removal and replacement. In this regard, it is preferredthat the nose portion 124 have a guideway 82 of a minimum diameterthroughout its length at least equal to the diameter of the bit 122 suchthat the nose portion 24 may be removed from the rear portion 22 withoutthe need to remove the bit 122 as may otherwise be the case in the eventthe guideway 82 may have a stepped configuration.

Operation of the driver attachment is now explained with particularreference to FIGS. 4 and 5. As seen in FIG. 4, the screws 16 to bedriven are collated to be held parallel and spaced from each other bythe plastic retaining strip 13.

In operation, a screwstrip 14 containing a number of screws 16 collatedin the plastic retaining strip 13 is inserted into the channelway 88with the first screw to be driven received within the guideway 82. Todrive the first screw into the workpiece 124, the power driver 11 isactivated to rotate the driver shaft 34. The driver shaft 34 and its bit122, while they are rotated, are reciprocally movable in the guideway 82towards and away from the workpiece 124. In a driving stroke, manualpressure of the user pushes the housing 18 towards the workpiece 124.With initial manual pressure, the forward end of the nose portionengages the workpiece 124 to compress spring 38 so as to move slide body20 relative the housing 18 into the housing 18 from an extended positionshown in FIG. 4 to a retracted position. On release of this manualpressure, in a return stroke, the compressed spring 38 moves the slidebody 20 back to the extended position thereby moving the housing 18 andthe driver shaft 34 away from the workpiece.

In a driving stroke, as the driver shaft 34 is axially moved towards theworkpiece, the bit 122 engages the screw head 17 to rotate the firstscrew to be driven. As is known, the plastic strip 13 is formed torelease the screw 16 as the screw 16 advances forwardly rotated by thedriver shaft 34. Preferably, the screw tip will engage in a workpiecebefore the head of the screw engages the strip such that engagement ofthe screw in the workpiece will assist in drawing the screw head throughthe strip to break the fragible straps, however, this is not necessaryand a screw may merely, by pressure from the drive shaft, be releasedbefore the screw engages the workpiece. Preferably, on release of thescrew 16, the plastic strip 13 deflects away from the screw 16 outwardlyso as to not interfere with the screw 16 in its movement into theworkplace. After the screw 16 is driven into the workpiece 124, thedriver shaft 34 axially moves away from the workpiece under the force ofthe spring 38 and a successive screw 16 is moved via the screw feedadvance mechanism from the channelway 88 through the access opening 86into the guideway 82 and into the axial alignment in the guideway withthe driver shaft 34.

The screw 16 to be driven is held in position in axial alignment withthe driver shaft 34 with its screw head 17 abutting the sidewall 83 inthe guideway 82. As a screw 16 to be driven is moved into thecylindrical guideway 82, a leading portion of the strip 13' from whichscrews have previously been driven extends outwardly from the guideway83 through the exit opening 87 permitting substantially unhinderedadvance of the screwstrip 14.

To assist in location of a screw to be driven within the guide tube 75,in the preferred embodiment the exit opening 87 is provided with arearwardly facing locating surfaced 125 adapted to engage and support aforward surface 222 of the strip 13. Thus, on the bit 122 engaging thehead of the screw and urging the screw forwardly, the screw may beaxially located within the guide tube 75 by reason not only of the headof the screw engaging the sidewall 83 of the guideway but also with theforward surface 222 of the strip 13 engaging the locating surface 125 ofthe exit opening 87. In this regard, it is advantageous that the forwardsurface 222 of the retaining strip 13 be accurately formed having regardto the relative location of the screws 16 and particularly the locationof the their heads 17. The forward surface 222 of the strip 13 may becomplementary formed to the locating surface 125 and if desired indexingnotches or the like may be provided in the forward surface 222 of thestrip 13 to engage with complementary notches or indents on the locatingsurface 125 of the entranceway to assist in indexing location of thestrip 13 relative the locating surface and enhance the location therebyof the screw 16 within the guide tube 75.

The preferred embodiment illustrated in FIG. 1 shows a screwdriverassembly driving a short length of a screwstrip. Strips of discretelength could be provided for example, one or two feet long which canmerely be manually fed into the channelway 88 when desired. Such stripsare preferably relatively stiff and self-supporting. Alternately, knowncartridges may be mounted to the assembly to carry a coil of thescrewstrip.

The driver attachment may be constructed from different materials ofconstruction having regard to characteristics of wear and the intendeduse of the attachment. Preferably, a number of the parts may be moldedfrom nylon or other suitably strong light weight materials. Parts whichare subjected to excessive wear as by engagement with the head of thescrew may be formed from metal or alternatively metal inserts may beprovided within an injection molded plastic or nylon parts. Theprovision of a removable nose portions 24 also has the advantage ofpermitting removable nose portion to be provided with surfaces whichwould bear the greatest loading and wear and which nose portions may beeasily replaced when worn.

In the preferred embodiment, the screwstrip 14 is illustrated as havingscrews extending normal to the longitudinal extension of the strip 13and in this context, the channelway 88 is disposed normal to thelongitudinal axis 52. It is to be appreciated that screws and otherfasteners may be collated on a screwstrip in parallel spaced relationhowever at an angle to the longitudinal axis of the retaining strip inwhich case the channelway 88 would be suitably angled relative thelongitudinal axis so as to locate and dispose each successive screwparallel to the longitudinal axis 52 of the driver shaft.

A preferred collated screwstrip 14 for use in accordance with thepresent invention is as illustrated in the drawings and particularlyFIG. 3 and are substantially in accordance with Canadian Patent1,054,982. The screwstrip 14 comprises a retaining strip 13 and aplurality of screws 16. The retaining strip 13 comprises an elongatethin band formed of a plurality of identical sleeves interconnected bylands 106. A screw 16 is received within each sleeve. Each screws 16 hasa head 17, a shank 208 carrying external threads 214 and a tip 15. Asshown, the external threads extend from below the head 17 to the tip 15.

Each screw is substantially symmetrical about a central longitudinalaxis 212. The head 17 has in its top surface a recess 213 for engagementby the screwdriver bit.

Each screw is received with its threaded shank 208 engaged within asleeve. In forming the sleeves about the screw, as in the manner forexample described in Canadian Patent 1,040,600, the exterior surfaces ofthe sleeves come to be formed with complementary threaded portions whichengage the external thread 214 of the screw 16. Each sleeve has areduced portion between the lands 206 on one first side of the strip 13.This reduced strength portion is shown where the strip extends abouteach screw merely as a thin strap-like portion or strap 220.

The strip 13 holds the screw 16 in parallel spaced relation a uniformdistance apart. The strip 13 has a forward surface 222 and a rearsurface 223. The lands 106 extend both between adjacent screws 16, thatis, horizontally as seen in FIG. 3, and axially of the screws 16, thatis, in the direction of the longitudinal axes 212 of the screws. Thus,the lands comprise webs of plastic material provided over an areaextending between sleeves holding the screws and between the forwardsurface 222 and the rear surface 223. A land 206 effectively is disposedabout a plane which is parallel to a plane in which the axes 212 of allthe screws lies. Thus, the lands 206 comprise a web which is disposedsubstantially vertically compared to the vertically oriented screws asshown in the figures. The lands 206 and the sleeves, in effect, aredisposed as continuous, vertically disposed strip 13 along the rear ofthe screws 16, that is, as a strip 13 which is substantially disposedabout a plane which is parallel to a plane containing the axes of allscrews.

Some screwstrips may bend to assume a coil-like configuration due toflexibility of the lands 206, such that, for example, the screwstripcould be disposed with the heads of the screws disposed into a helicalcoil, that is, the plane in which all the axes 212 of the screws lie mayassume a coiled, helical configuration to closely pack the screws foruse. Having the lands 206 and sleeves as a vertically extending weblying in the plane parallel that in which the axes 212 permits suchcoiling.

The invention is not limited to use of the collated screwstripsillustrated. Many other forms of screwstrips may be used such as thoseillustrated in U.S. Pat. No. 3,910,324 to Nasiatka; U.S. Pat. No.5,083,483 to Takaji; U.S. Pat. No. 4,019,631 to Leidegard et al and U.S.Pat. No. 4,018,254 to DeCaro.

While the invention has been described with reference to preferredembodiment, the invention is not so limited. Many variations andmodifications will now occur to persons skilled in the art. For adefinition of the invention, reference is made to the appended claims.

We claim:
 1. An apparatus for driving with a power driver a screwstripcomprising threaded fasteners, such as screws or the like, which arejoined together in a strip comprising:a housing; an elongate drivershaft for operative connection to a power driver for rotation therebyand defining a longitudinal axis; a slide body coupled to the housingfor displacement parallel to the axis of the driver shaft between anextended position and a retracted position; the slide body having aguide channel for said screwstrip transverse to the axis, a shuttlecarried on the slide body movable relative the slide body transverse tothe axis towards and away from the axis, the shuttle carrying an advancepawl for engagement with the screwstrip to advance the screwstrip withmovement of the shuttle towards the axis to place successive of thefasteners into axial alignment with the driver shaft for driving by thedriver shaft, a lever having a first end coupled to the shuttle and asecond end coupled to the housing whereby movement of the slide bodyaxially relative the housing (a) towards the extended position moves theshuttle towards the axis and (b) away from the extended position movesthe shuttle away from the axis, a bearing member on the slide body whichengages the lever intermediate the first end and the second end of thelever when the slide body is proximate the extended postion such thatwhen the slide body moves axially towards the extended position, thebearing member urges the lever to assist moving the shuttle towards theaxis.
 2. An apparatus as claimed in claim 1 wherein the shuttle isslidably mounted to the slide body for sliding along a set pathway. 3.An apparatus as claimed in claim 2 wherein the shuttle slides along alinear beam.
 4. An apparatus as claimed in claim 1 including a springbiasing the slide body forwardly relative the housing to the extendedposition.
 5. An apparatus as claimed in claim 1 wherein the first end ofthe lever is pivotally connected to the shuttle.
 6. An apparatus asclaimed in claim 5 wherein the second end of the lever is pivotallyconnected to the housing.
 7. An apparatus as claimed in claim 5 whereinthe second end of the lever includes a lost motion slot,a pin is carriedon the housing, the pin is slidable in the lost motion slot and thelever is pivotable about the pin relative the housing.
 8. An apparatusas claimed in claim 2 wherein the pathway is disposed in a first plane,the first end of the lever is pivotally connected to the shuttle forpivoting relative the shuttle about an axis normal the first plane andthe second end of the lever is pivotally connected to the housing forpivoting relative the housing about an axis normal the first plane. 9.An apparatus as claimed in claim 1 wherein the slide body is disposedradially about the drive shaft,the housing has a side wall disposedgenerally radially about the slide body, the side wall of the housinghaving an axially extending keyway radially through the side wall, theslide body having a key member extending radially outwardly therefromslidably received in the keyway, the bearing member provided on the keymember radially outwardly of the side wall of the housing.
 10. Anapparatus as claimed in claim 9 wherein the keyway and key membercooperate to limit sliding of the slide body and housing between thefully extended and fully retracted positions and prevent relativerotation of the slide body and housing about the axis.
 11. An apparatusas claimed in claim 10 wherein the guide channel comprises a radialextension of the slide body, the shuttle carried on the radial extensionon a first side of the apparatus,the first end of the lever coupled tothe shuttle on the first side of the apparatus, the second end of thelever mounted to the housing on the first side of the apparatus, thelever in extending from its first end on the shuttle to its second endon the housing extends across the keyway axially forward of the bearingmember for engagement by the bearing member.
 12. An apparatus as claimedin claim 1 wherein the slide body having guide mechanism to locatesuccessive of the screws advanced via the guide channel to be axially inalignment with the driver shaft for engagement in driving of the screwsfrom the guide means by the driver shaft.
 13. An apparatus as claimed inclaim 1 including a return pawl to engage the screwstrip and preventmovement of the screwstrip in a direction opposite the direction inwhich the screwstrip is advanced and a release mechanism for releasingsaid return pawl.
 14. An apparatus as claimed in claim 9 wherein aspring is disposed coaxially about the driver shaft engaging the housingat one end and the slide body at another end to urge the slide body tothe extended position.
 15. An apparatus as claimed in claim 7 wherein apin is carried on the shuttle, the first end of the lever including abore, the pin received in the bore such that the lever is pivotableabout the pin relative the shuttle.
 16. An apparatus as claimed in claim1 wherein the slide body comprises a nose portion which is removablefrom a rear portion of the slide body carrying the bearing plate, thelever releaseably engageable with one of the shuttle and the housing forreplacement of the removable nose portions with other similar removablenose portions.
 17. An apparatus as claimed in claim 1 wherein the leverhas an axially rearwardly directed cam surface for engagement by axiallyforwardly directed bearing surfaces of the bearing member.
 18. Anapparatus as claimed in claim 1 wherein with the slide body locatedrelative the housing in a fully extended position, the bearing plateengages the lever to assist the shuttle in urging the screwstrip towardsthe axis to maintain a screw in axial alignment with the driver shaft.